Wind turbine blades used for horizontal axis wind turbines for generating electrical power from the wind can be rather large and may today exceed 70 meters in length and 4 meters in width. The blades are typically made from a fibre-reinforced polymer material and comprising an upwind shell part and a downwind shell part. Due to the size and fragility of these large rotor blades, the blades may be damaged during transport as well as during loading and unloading. Such damages may seriously degrade the performance of the blades. Therefore, the blades need to be carefully packaged in order to ensure that they are not damaged.
However, due to the increasing length of modern wind turbine blades, it is gradually becoming more complicated and expensive to transport the blades. It is not uncommon that the transportation costs amount to 20 percent of the total costs for manufacturing, transporting and mounting the wind turbine blade on the rotor of a wind turbine blade. Also, some blades are transported to the erection site through different modes of transport, such as by truck, train and ship. Some of these modes of transports may have restrictions on large loads, maximum heights, maximum widths, maximum distances between transport frames or supports, for instance dictated by local regulations. Therefore, there exists a logistic problem of providing transport solutions that are suitable for various types of transport.
Overall, there is a demand for making transport solutions simpler, safer and cheaper. The prior art shows various solutions for transporting more than one rotor blade using a single container or other packaging system, which is an obvious way to reduce the transport costs. However, the afore-mentioned restrictions and limits may increase the difficulty of transporting a plurality of blades using the same packaging system. EP1387802 discloses a method and system for transporting two straight wind turbine blades, where the root end of a first blade is arranged in a first package frame, and the tip end of a second, neighbouring blade is arranged in a second package frame that is arranged next to and connected to the first package frame with the effect that the blades are stored compactly alongside each other in a “tip-to-root” arrangement. However, in this transport system the tip end frames support the blades at the very tip of the blades, where they are mechanically most fragile. Further, the package frames are arranged at the root end face and the blade tip. Therefore, the distance between the package frames are approximately equal to the length of the blades. For very long blades of 45 meters or longer, this might not be possible due to local regulations and restrictions on transport.
US 2011/0142660 discloses a wind turbine blade, which is provided with an integrated attachment bore through the spar caps of the blades. The attachment bores are structurally configured for receipt of a handling mechanism for supporting the blade during transport. Two blades may be arranged in a tip-to-root configuration, where the tip end of one blade is arranged nearly adjacent the root end of a second blade.
WO 2011/098086 discloses a system for transporting a wind turbine component via a first railcar and a second railcar. One embodiment shows the transport of two blades in a tip-to-root configuration, where a first frame is mounted on a first support member slidingly and rotatingly coupled to the first railcar, and a second frame is mounted on a second support member rotatingly coupled to a second rail car. The tip end of one blade is arranged nearly adjacent the root end of a second blade.
It is therefore an object of the invention to obtain a new method and system for storing and transporting a plurality of wind turbine blades, which overcome or ameliorate at least one of the disadvantages of the prior art or which provide a useful alternative.